The present invention relates generally to stents, and more particularly to an implantable bifurcated stent used to reinforce the bifurcation of the aorta into arteries leading to the lower limbs and a method for positioning such a stent within a blood vessel.
Stents are commonly used to repair compromised blood vessels in the body. Such stents may be used to repair compromised coronary arteries which have become narrowed or altogether blocked by the build up of plaque. They may also be used to replace compromised blood vessels, such as the aorta, which have developed enlarged, weakened areas known as aneurysms. In the aorta, aneurysms may often occur in the areas where the aorta divides into two secondary arteries, such as the two common iliac arteries, which supply blood to the lower limbs.
Previously, such aneurysms were repaired by surgery by making an incision in the patient's body and cutting into the aorta and implanting a tubular graft into the artery to replace the portion of the artery compromised by the aneurysm.
This surgery poses a problem where the aneurysm occurs at locations where one blood vessel branches off into two subsidiary blood vessels. One solution for arterial repairs at such a location has been proposed in European Patent Application EP-A-0 551 179, published Jul. 14, 1993 wherein two separate bypass grafts are introduced into an aortic branch. These two grafts are intraluminally delivered through the artery to the aneurysm and secured therein by means of two dilation catheters. This structure relies solely upon the expansion of the bilateral grafts against each other within the aorta and therefore requires very accurate sizing of the grafts and placement in the aorta. This structure may be problematic in that the aortic ends of the grafts may work themselves free under arterial pressure.
It is therefore desirable to develop a graft, or stent, for use in bifurcated blood vessels which is self-supporting and may be advantageously used to reinforce bifurcated portions of the aorta as well as other blood vessels.
Such a stent can be employed in an advantageous manner to reinforce the bifurcation of the aorta or another artery into the two smaller arteries leading to the lower limbs. With the present state of technology such a stent is not available and in the case of a lesion on the artery, it is often necessary to replace the entire section of the artery by a new, artificial blood vessel section (a bifurcation prosthesis). The surgery involved in such a procedure usually lasts several hours, entails a high degree of risk and is a great burden to the patient.
The present invention is therefore directed to a stent which makes the above described surgeries superfluous and is characterized by a first, or primary, stent placed inside an artery at the level of the bifurcation and at least two cylindrical secondary stents, each of which is partially placed within the arterial sections branching off of the artery, and with the remaining sections of the secondary stent being placed inside the lumen of the first stent.
In its preferred embodiment the present invention provides a bifurcated stent assembly having a Y-shaped configuration. The Y-shaped stent includes, as mentioned above, a base or primary stent which is fixed securely in the artery near to the location at which it divides into two branch arteries. The secondary stents are positioned both inside this first stent and inside the branching arteries and are fixed in a reliable and sealing manner to the first stent at one end and to the branching artery on the other end.
In particular, when stents are used which are disclosed in applicant's European patent application EP-A0 521 573 and EP-A-0 617 930 in forming the bifurcated stent assembly, a reliable and sealed anchoring within the bifurcated blood vessels is obtained as a result of the specific configuration of this stent.
Accordingly, it is a general object of the present invention to provide a bifurcated stent for intraluminal delivery to a bifurcated artery affected by lesions.
It is another object of the present invention to provide a bifurcated stent assembly for intraluminal delivery comprising a first primary stent having a partially conical shape and at least two secondary stents, each having a cylindrical configuration, the primary stent being intraluminally delivered to the arterial bifurcation and providing a base, or support, for the secondary stents.
It is still another object of the present invention to provide a bifurcated stent having a base portion which is placed within an artery upstream of and proximate to the affected area of the artery, the base portion providing an anchoring surface within the artery, and a number of secondary cylindrical stents which are intraluminally delivered to the affected arterial area and which extend through the base portion into the bifurcated arteries, the upstream ends of the secondary stents being anchored to the arteries by being joined to the base portion while the downstream, distal ends of the secondary stents extend into the branch arteries.
It is still a further object of the present invention to provide a method of repairing or reinforcing bifurcated blood vessels by first delivering and attaching an anchoring stent to an artery and subsequently delivering and attaching secondary stents to the anchoring stent and to the bifurcations of the artery.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.